1. Technical Field
The present invention relates generally to a liquid-crystal display for use in a small-sized radio transceiver, and more particularly to a shield attached to an EL (electroluminescence) plate connected to ground for reducing noise generated from a liquid-crystal driver, interfering with radio reception of an antenna.
2 Background of Related Art
Generally, small radio transceivers are equipped with a liquid-crystal display, a liquid-crystal driver controlling the liquid-crystal display for displaying received image information, and a shield plate covering the liquid-crystal driver.
FIG. 6 shows a typical liquid-crystal display for use in small radio transceivers which includes a liquid-crystal plate 21 for displaying characters, printed boards 22 having mounted thereon the liquid-crystal plate 21 and a liquid-crystal driver 23, an antenna 24 for receiving radio signals, and a shield plate 25 for covering the liquid-crystal driver 23,
In this type of liquid-crystal display, the number of characters to be indicated on the liquid-crystal plate 21 is relatively small. The liquid-crystal plate 21 is thus designed to indicate characters over at most two lines, as shown in FIG. 6. Specifically, a large-sized display covering the whole of the radio transceiver is not required. Noise entering the antenna 24 from the liquid-crystal driver 23 can be reduced by locating the liquid-crystal driver 23 away from the antenna 24 or covering it with a shield plate so that the noise does not interfere with radio reception of the antenna 24.
However, in recent years, the transmission speed of small radio transceivers is increased for increasing information elements to be transmitted, thus requiring a large-screen display capable of indicating characters over four or more lines, for example. Additionally, the small transceivers are further required to be small and compact.
In order meet such requirements, the operational speed and performance of a CPU used in small radio transceivers have been improved, and small radio transceivers using large-sized displays capable of displaying a great deal of information have been developed. Such small radio transceivers however encounter the drawback in that a liquid-crystal driver generates noises with increase in operational speed thereof, which greatly interfere with the radio reception.
In such a small radio transceiver, a liquid-crystal driver is usually not mounted on a printed board and formed with IC chips mounted on a COB (Chip On Board) with TAB (Tape Automated Bonding), connected to a liquid-crystal plate. Thus, the interval between the COB and the liquid-crystal plate is short, and it is difficult to dispose a shield plate between the COB and the liquid-crystal plate, thus resulting in a further increase in noise.